System and method for insertion of flexible spinal stabilization element

ABSTRACT

A method of inserting a spinal stabilization system into a patient generally comprises inserting a first positioning tool through a first location on a patient&#39;s skin and along a path generally toward a first vertebral anchor, coupling an end of the first positioning tool to the first vertebral anchor, positioning at least a portion of a delivery device over a connecting element, and inserting the delivery device and the connecting element through the patient&#39;s skin at the first location and along at least a portion of the first positioning tool. The first positioning tool is configured to facilitate directing the delivery device and connecting element generally toward a second vertebral anchor within the patient&#39;s body.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/718,052, filed Sep. 28, 2017, now issued as U.S. Pat. No. 9,782,203,which is a continuation of U.S. patent application Ser. No. 14/800,309,filed Jul. 15, 2015, now issued as U.S. Pat. No. 9,277,940, which is acontinuation of U.S. patent application Ser. No. 12/025,984, filed Feb.5, 2008, the contents of which are fully incorporated herein byreference.

FIELD OF THE INVENTION

This invention relates to surgical methods and associated installationsystems for spinal stabilization, and more particularly to such methodsand systems that facilitate inserting a flexible spinal stabilizationelement into a patient.

BACKGROUND

One of the most common methods for treating abnormal curvature of thespine and spinal disorders is to immobilize a portion of the spine toallow treatment. Traditionally, immobilization has been accomplished byrigid stabilization. For example, in a conventional spinal fusionprocedure, a rigid fixation rod is installed between pedicle screwssecured to adjacent vertebrae. The fixation rod cooperates with thescrews to immobilize the two vertebrae relative to each other so thatfusion may occur.

More recently, dynamic stabilization has been used in spinal treatmentprocedures. Dynamic stabilization permits enhanced mobility of the spinewhile also providing sufficient stabilization to effect treatment. Oneexample of a dynamic stabilization system is the Dynesys® systemavailable from Zimmer Spine, Inc. of Edina, Minn. Such dynamicstabilization systems typically include a flexible, tubular spacerpositioned between pedicle screws installed in adjacent vertebrae of thespine. The spacer is positioned between the pedicle screws and aflexible cord is threaded through the spacer. The flexible cord is alsosecured to heads of the pedicle screws by set screws, thereby retainingthe spacer between the pedicle screws while cooperating with the spacerto permit mobility of the spine.

The dynamic stabilization systems described above and others areinstalled in a patient during a surgical procedure. Patient recoveryfrom such surgical procedures is greatly enhanced if the tissue, muscle,and other parts of the patient that are displaced and affected by thesurgery are minimized, including the size and severity of the requiredincisions. For example, the cord may be inserted through an incisionused to implant one of the pedicle screws and then advanced to itsinstalled position between the pedicle screws. Due to its flexiblenature, however, the cord can be difficult to maneuver through thetissue. Therefore, systems and methods that facilitate the insertion ofsuch flexible cords and similar elements are highly desirable.

SUMMARY

A method of inserting a spinal stabilization system into a patientgenerally comprises inserting a first positioning tool through a firstlocation on a patient's skin and along a path generally toward a firstvertebral anchor within the patient's body. An end of the firstpositioning tool is then coupled to the first vertebral anchor. Afterpositioning at least a portion of a delivery device over a connectingelement, the delivery device and the connecting element are insertedthrough the patient's skin at the first location and along at least aportion of the first positioning tool. The first positioning tool isconfigured to facilitate insertion of the delivery device and connectingelement, the delivery device and connecting element being directinggenerally toward a second vertebral anchor within the patient's body.Eventually, a first portion of the connecting element is secured to thesecond vertebral anchor and the delivery device is removed from theconnecting element to expose a second portion of the connecting element.A spacer may then be advanced over the connecting element beforesecuring the second portion to the first vertebral anchor.

In one embodiment, at least a portion of the delivery device is receivedin an elongated slot defined by the first positioning tool when insertedthrough the patient's skin. After securing the first portion of theconnecting element to the second vertebral anchor and removing thedelivery device to expose the second portion of the connecting element,the second portion is positioned within the elongated slot. A tensioningtool may be inserted through the elongated slot to direct the secondportion into a receiving channel defined by the first vertebral anchor.Additional length of the connecting element extending beyond of thereceiving channel may be pulled to place the connecting element intension before securing the second portion to the first vertebralanchor.

In another embodiment, the spinal stabilization system further includesa third vertebral anchor positioned between the first and secondvertebral anchors. Using the techniques briefly described above and setforth in greater detail below, the connecting element is secured to thefirst, second, and third vertebral anchors so as to form a multi-leveltreatment system.

In another aspect or embodiment, at least two spacers for can beprovided for placement between the vertebral anchors, the first spacerhaving a first elasticity and placed between first and second vertebralanchors and the second spacer having a second elasticity placed betweensecond and third vertebral anchors.

In another embodiment, the connecting element for connection to thevertebral anchors can include a first portion with a first elasticityfor connection between the first and second vertebral anchors and asecond portion with a second elasticity for connection between thesecond and third vertebral anchors.

A system for dynamic stabilization system of a patient's spine is alsoprovided. The system generally comprises first and second vertebralanchors configured to be secured at first and second locations withinthe patient's body, a connecting element having first and secondportions configured to be received by the first and second vertebralanchors a delivery device configured to be positioned over theconnecting element, and a first positioning tool having an endconfigured to couple to the first vertebral anchor. The delivery deviceis more rigid than the connecting element and is retractable along theconnecting element. Additionally, the first positioning tool includes anelongated slot configured to facilitate guiding the delivery device andconnecting element along a path generally toward the second vertebralanchor.

In one aspect or embodiment, the delivery device includes a first sheathmember coupled to a second sheath member at an articulating joint sothat the angle of the first sheath member relative to the second sheathmember may be adjusted. The articulating joint may be configured to lockthe first sheath member at various angles relative to the second sheathmember.

In another aspect or embodiment, a plurality of spacers having differentelastic characteristics may be provided, allowing the surgeon to selecta spacer based on its rigidity or elasticity to treat specific patientconditions. A plurality of connecting elements having different elasticcharacteristics may also be provided, allowing the surgeon to select aconnecting element based on its rigidity or elasticity to treat specificpatient conditions.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate exemplary embodiments of theinvention.

FIG. 1 is a schematic view showing a portion of a spinal stabilizationsystem according to one embodiment;

FIG. 1A is a schematic view showing a positioning tool in the spinalstabilization system of FIG. 1;

FIG. 2 is a perspective view showing an end of a positioning tool and avertebral anchor used in the spinal stabilization system of FIG. 1;

FIG. 3 is a perspective view showing a portion of a delivery device anda connecting element according to one embodiment for use in the spinalstabilization system of FIG. 1;

FIGS. 3A-3G are schematic views sequentially illustrating one method ofinserting a flexible spinal stabilization system into a patient:

FIG. 4 is a schematic view similar to FIG. 3A showing a delivery deviceaccording to an alternative embodiment;

FIG. 5 is a perspective view of a delivery device and a connectingelement according to another embodiment for use in the spinalstabilization system of FIG. 1;

FIGS. 5A-5C are schematic views sequentially illustrating another methodof inserting a flexible spinal stabilization system into a patient:

FIGS. 6A-6C are schematic views sequentially illustrating yet anothermethod of inserting a flexible spinal stabilization system into apatient;

FIGS. 7A-7C are schematic views sequentially illustrating yet anothermethod of inserting a flexible spinal stabilization system into apatient; and

FIGS. 8A-8D are schematic views sequentially illustrating yet anothermethod of inserting a flexible spinal stabilization system into apatient.

DETAILED DESCRIPTION

The following description focuses primarily upon techniques and toolsfor inserting the components of a stabilization system 10 (FIG. 3G)within a patient's body 12. However, by way of background and withreference to FIG. 3G, the stabilization system 10 generally includesfirst and second vertebral anchors 14, 16 secured to respective firstand second vertebrae 18, 20 in the patient's body 12, a connectingelement 22 configured to extend between the first and second anchors 14,16, and a spacer, configured to be received over the connecting element22 between the first and second vertebral anchors 18, 20. The connectingelement 22 may be, for example and without limitation, a flexibleelement such as a cord formed from polyethylene terephthalate (PET),titanium or metal materials, or other suitable materials recognized bythose skilled in the art. In one embodiment, the surgeon can be providedwith several connecting elements 22 of varying elasticity to allow thesurgeon to choose the connecting element based on the patient'scondition.

The spacer 24 may be a flexible element formed, for example and withoutlimitation, from polycarbonate-urethane (PCU), PEEK, polymeric and/orflexible materials, or other suitable materials recognized by thoseskilled in the art. In alternative embodiments, the spacer can be formedfrom a rigid material. In one embodiment, the stabilization system 10includes elements of the Dynesys® system available from Zimmer Spine,Inc. of Edina, Minn. Those skilled in the art will appreciate, however,that the techniques and tools described below may also apply to otherstabilization systems having similar components and/or operating uponsimilar principles.

Additionally, those skilled in the art will appreciate that thestabilization system can be used in connection with other spinalimplants, such as interbody fusion implants, biologic materials,artificial disks, nucleus repair materials, nucleus replacementimplants, plates, screws, vertebral body replacement implants,interspinous process spacer implants, bone void filler materials andbone cement materials.

The first and second vertebral anchors 14, 16 may be inserted into thepatient's body 12 and secured using any technique known in the art. Inone embodiment, a first incision 30 is made at a first location on thepatient's skin 28 generally aligned above the first vertebra 18. Thefirst vertebral anchor 14 is inserted through the first incision 30 andadvanced through the patient's body 12 so that it may be secured to thefirst vertebra 18.

The second vertebral anchor 16 may be inserted into the patient's body12 in a similar manner. Specifically, a second incision 32 may be madeat a second location on the patient's skin 28 generally aligned abovethe second vertebra 20. The second vertebral anchor 16 is advanced intothe patient's body 12 so that it may be secured to the second vertebra20. Advantageously, the first and second incisions 30, 32 may be sizedso that minimally invasive, percutaneous techniques and/orretractor-based techniques may be used to advance and install the firstand second vertebral anchors 14, 16 in the patient's body 12. However,the first and second incisions 30, 32 may alternatively be sized fortraditional, open surgical procedures as well.

A wide variety of vertebral anchors may be used with the stabilizationsystem 10. The first and second vertebral anchors 14, 16 shown in thedrawings are uniaxial pedicle screws each having a head 36 with firstand second arms 38, 40 (FIG. 2) defining a receiving channel 42 and ashaft 44 extending from the head 36. The shaft 44 may include threads 46(FIG. 2) to facilitate securing the first and second vertebral anchors14, 16 to the respective first and second vertebrae 18, 20. Again,however, the first and second vertebral anchors 14, 16 are merelyexemplary in nature. Other types of vertebral anchors (not shown), suchas polyaxial pedicle screws, hooks, or other means for engaging thespine, may alternatively be used in the stabilization system 10.

Now referring to FIGS. 1-3, various components for inserting thestabilization system 10 into the patient's body 12 are shown.Specifically, FIGS. 1 and 2 show a first positioning tool 50 insertedthrough the first incision 30 and into the patient's body 12 along apath generally toward the first vertebral anchor 14.

In other embodiments, the first positioning tool 50 can be modified toprovide for connection of the first positioning tool 50 to the vertebralanchor 14 outside the patient, the first positioning tool 50 andvertebral anchor 14 inserted through the incision 30 as a single unit.In such a configuration, the first positioning tool 50 can be used toguide the vertebral anchor 14 to the vertebral body 18 for securement tothe vertebral body. In this embodiment, a k-wire (not shown) that issecured to the vertebral body 18 can be used in connection with acannulated vertebral anchor 14 to assist in proper securement andpositioning of the vertebral anchor 14. This method of securement ofvertebral anchors to vertebral bodies may be used for any vertebralanchor used in the stabilization system 10.

The first positioning tool 50 includes a first end 52 that may becoupled to the head 36 of the first vertebral anchor 14 using anysuitable technique. In one embodiment, the first positioning tool 50includes first and second bifurcations 54, 56 defining an elongated slotor cavity 58 there between. The first and second bifurcations 54, 56 areeach configured to be received over the respective first and second arms38, 40 on the head 36 of the first vertebral anchor 14. The first andsecond bifurcations 54, 56 may also include one or more engagementfeatures designed to mate with a corresponding engagement feature on thehead 36. For example, the first and second bifurcations 54, 56 mayinclude a tab or projection 60 configured to be received in a slot 62formed on an outer surface 64 of the head 36. Other examples of possiblearrangements for coupling the first end 52 of first positioning tool 50to the first vertebral anchor 14 are shown and described in U.S. patentapplication Ser. Nos. 11/737,151 and 11/743,481, the disclosures ofwhich are fully incorporated herein by reference.

The elongated slot 58 may extend along the entire length of the firstpositioning tool 50, which may include a handle (not shown) at alocation outside the patient's body 12. Alternatively, the elongatedslot 58 may only extend across a certain length of the first positioningtool 50. Furthermore, the elongated slot 58 need not extend all the waythrough the first positioning tool 50. The first positioning tool 50 maytherefore have a substantially U-shaped cross section along its lengthrather than the first and second bifurcations 54, 56.

Although FIG. 1 shows the first vertebral anchor 14 substantiallyaligned along an axis 68 and the first positioning tool 50 coupled tothe first vertebral anchor 14 along the axis 68, the first positioningtool 50 may alternatively be positioned and maintained at an anglerelative to the axis 68. For example, FIG. 1 shows the first positioningtool 50 positioned at an angle .theta. to the axis 68. In oneembodiment, the angle .theta. is approximately 7.degree. In anotherembodiment, the angle .theta. is approximately 14.degree. In yet anotherembodiment, the first positioning tool 50 may be coupled to the firstvertebral anchor 14 in a manner that allows the angle .theta. to beadjusted as needed.

FIG. 3 shows a delivery device 70 positioned over the connecting element22. The delivery device 70 may be made from any type of materialsuitable for insertion into a patient's body 12. In one embodiment, thedelivery device 70 is constructed from flexible polyethylene tubinghaving a rigidity greater than that of the connecting element 22. Inother embodiments, the delivery device 70 may be constructed frommaterials such as metal to provide even greater rigidity. Although thedelivery device 70 is shown as being a tubular element, otherconfigurations are possible in which the delivery device 70 does notentirely surround the connecting element 22. For example, the deliverydevice 70 may alternatively be a helical element (not shown) or someother structure extending over a length of the connecting element 22 toprovide added rigidity for reasons discussed below. Additionally, thedelivery device 70 may comprise multiple component parts assembledtogether from the same or a variety of different materials.

In some embodiments, the connecting element 22 may be provided with anend portion 71 that is more rigid than the remainder of the connectingelement 22. This may be achieved by constructing the connecting element22 with different material properties at the end portion 71 or bymounting a separate component to the connecting element 22. For example,as shown in FIG. 3, the end portion 71 may be a bullet-shaped nose orsimilar structure coupled to the connecting element 22. The nose may beconstructed of metal or other rigid material and may be tapered to a tip73 to facilitate movement through tissue. The material of the endportion 71 may also be selected to help identify the location of the endportion 71 as the connecting element 22 is advanced through tissue. Forexample, the end portion 71 may be constructed from radiopaque materialso as to serve as a marker during a surgical procedure.

With reference to FIGS. 3A-3G, a method of inserting the stabilizationsystem 10 into the patient's body 12 will now be described. Afterinserting the first and second vertebral anchors 14, 16 into thepatient's body 12, the connecting element 22 may be positioned relativeto the first and second vertebral anchors 14, 16 using the firstpositioning tool 50 and delivery device 70. Specifically, the firstpositioning tool 50 may be inserted through the first incision 30 andcoupled to the head 36 of the first vertebral anchor 14 in the mannerdiscussed above. The delivery device 70, which is at least partiallypositioned over the connecting element 22, may then be inserted throughthe first incision 30 and along at least a portion of the firstpositioning tool 50.

The delivery device 70 may have a width smaller or larger than the widthof the elongated slot 58. In either embodiment, the first positioningtool 50 facilitates directing the delivery device 70 generally towardthe second vertebral anchor 16. For example, FIG. 3A shows the deliverydevice 70 having a diameter smaller than the width of the elongated slot58 so that the delivery device 70 may be received within the elongatedslot 58. Such an arrangement enables the delivery device 70 to beinserted into the patient's body 12 through the same channel establishedby the first positioning tool 50. Additionally, the elongated slot 58 insuch an embodiment may be provided with an engagement feature (notshown) configured to cooperate with a mating engagement feature (notshown) on the delivery device 70. The engagement features may be, forexample, a tongue provided in the elongated slot 58 and a mating grooveor track provided on the outer surface of the delivery device 70.Alternatively, the delivery device 70 may be provided with a tongue andthe elongated slot 58 may be provided with a groove or track. Suchengagement features help guide the delivery device 70 along a desiredpath through elongated slot 58 so that the delivery device 70 isultimately directed toward the second vertebral anchor 16.

If the delivery device 70 has a diameter slightly larger than the widthof the elongated slot 58, the delivery device 70 may still be partiallyreceived in the elongated slot 58. FIG. 4 shows one example of such anembodiment, with prime (′) marks being used to designate structure thatslightly differs from FIG. 3A. A surgeon may slide the delivery device70′ along the first positioning tool 50 to facilitate directing thedelivery device 70′ generally toward the second vertebral anchor 16. Forexample, the delivery device 70′ may be formed with a desired degree ofcurvature. By using the first positioning tool 50 for guidance and/orleverage, the surgeon can guide the delivery device 70′ along a pathcorresponding to its curvature.

Regardless of how the first positioning tool 50 facilitates directingthe delivery device 70 (or 70′) generally toward the second vertebralanchor 16, the strength of the delivery device 70 and its ability towithstand compression forces enables it to be advanced through tissue 72in the patient's body 12 without being significantly deflected. A firstportion 74 of the connecting element 22 may remain exposed when theconnecting element 22 is inserted with the delivery device 70, but doesnot extend an appreciable distance so that the connecting element 22does not adversely affect the insertion of the delivery device 70through the tissue 72. Indeed, when the end portion 71 is in the form ofa bullet-shaped nose (as shown), the shape and rigidity of the nose mayfacilitate movement of the connecting element 22 through the tissue 72.

The delivery device 70 may be manipulated while being advanced along thefirst positioning tool 50 until the first portion 74 of the connectingelement 22 is received in or near the receiving channel 42 of the secondvertebral anchor 16, as shown in FIG. 3B. To this end, the deliverydevice 70 may be passed through the first incision 30 and directedtoward the second vertebral anchor 16 until it abuts and/or confronts agenerally flat surface 76 defined by the head 36. If the first portion74 of the connecting element 22 remains exposed during this insertion,the first portion 74 may be received in the receiving channel 42 of thesecond vertebral anchor 16 without additional steps. If the deliverydevice 70 is positioned over the first portion 74 during insertion, theconnecting element 22 may then be pushed through the delivery device 70until the first portion 74 extends through the receiving channel 42.

Alternatively, the delivery device 70 may be constructed from a flexibleshape memory material, such as Nitinol. The shape memory material may betemperature-dependent such that the delivery device 70 has a normallystraight configuration at room temperature, but assumes a curvedconfiguration once placed within the patient's body 12 (where it isexposed to body temperatures). The delivery device 70 may still bepassed through the patient's body 12 and directed generally toward thesecond vertebral anchor 16 while using the first positioning tool 50 forguidance and/or leverage.

In some instances, the delivery device 70 may not be directly alignedwith the receiving channel 42 after directing the connecting element 22toward the second vertebral anchor 16. If necessary or desired,additional tools (not shown) may be inserted through the second incision32 to help properly position the first portion 74 within the receivingchannel 42. Because the receiving channel 42 is open, the first portion74 may be easily received by the second vertebral anchor 16 in atop-loading fashion. Radiographic images can be obtained to determinethe proper positioning of the first portion 74 of the connecting element22. The end portion 71 can be formed of a material that facilitates theidentification of the proper placement of the connecting element 22.

Before or after the first portion 74 of the connecting element 22 isreceived in the receiving channel 42, a second positioning tool 80 maybe inserted through the second incision 32 and along a path generallytoward the second vertebral anchor 16. The second positioning tool 80includes a second end 82 configured to be coupled to the head 36 of thesecond vertebral anchor 16 in the same manner as the first end 52 of thefirst positioning tool 50 and the head 36 of the first vertebral anchor14. A fastener 84 may then be passed through the second incision 32 andpercutaneously delivered to the receiving channel 42. For example, thefastener 84 may be delivered through an elongated slot 86 defined in thesecond positioning tool 80, as shown in FIG. 3B. The fastener 84 issecured within the receiving channel 42 so that the first portion 74 ofthe connecting element 22 is retained (e.g., compressed) between thefastener 84 and the second vertebral anchor 16.

In one embodiment, the fastener 84 is a set screw having externalthreads go that engage internal threads 92 (FIG. 2) provided in thereceiving channel 42 of the second vertebral anchor 16. The fastener 84may be delivered through the second positioning tool 80 and tightenedusing a driving tool 94, as shown in FIG. 3C (with the secondpositioning tool 80 shown in phantom for clarity). The secondpositioning tool 80 stabilizes the second vertebral anchor 16 as the setscrew is rotated to engage the internal threads 92. Thus, the secondpositioning tool 80 may serve as an anti-torque instrument to counteractthe forces applied by the driving tool 94. In other embodiments, thefirst portion 74 of the connecting element 22 may be secured to the head36 of the second vertebral anchor 16 using different types of fastenersor other elements. For example, the second vertebral anchor 16 mayalternatively be shaped to cooperate with a cap (not shown) forretaining the first portion 74 of the connecting element 22.

Once the first portion 74 of the connecting element 22 is secured to thesecond vertebral anchor 16, the second positioning tool 80 may beremoved from the patient's body 12 through the second incision 32. Thedelivery device 70 may also be removed from the connecting element 22 toexpose a second portion 96 of the connecting element 22. As shown inFIG. 3C, the delivery device 70 is removed through the first incision 30in the patient's skin 28. The tissue 72 surrounding the connectingelement 22 effectively maintains the connecting element 22 in positionwhile the delivery device 70 is removed.

FIG. 3D illustrates the spacer 24 being advanced through the firstincision 30 and over the connecting element 22. The second positioningtool 80 and driving tool 94 may be removed before or after the spacer 24is advanced. Additionally, although the first positioning tool 50 isshown as remaining within the patient's body 12, it will be appreciatedthat the first positioning tool 50 may alternatively be removed throughthe first incision 30 prior to this step as well. The spacer 24 may beadvanced along the length of the connecting element 22 until a first end98 of the spacer 24 confronts the generally flat surface 76 of the head36. If desired, a pushing instrument (not shown) may be used to aid inmovement of the spacer 24 through tissue 72 and along the connectingelement 22. The pushing instrument may be inserted through the firstincision 30 and adapted to engage a second end 100 of the spacer 24 topush the spacer 24 generally in the direction of arrow 102.Alternatively or additionally, the pushing instrument may be adapted toengage a portion of the spacer 24 between the first and second ends 98,100 to adjust the orientation of the spacer 24 relative to the firstvertebral anchor 14 and/or second vertebral anchor 16. In such anembodiment, the pushing instrument may be inserted through a separateincision (not shown) or the second incision 32.

Prior to insertion of the spacer 24, the surgeon can determine thedistance between vertebral anchors 14, 16 and size the spacer 24 outsidethe patient to a length that achieves a desired patient outcome. Forexample, if the surgeon hopes to achieve posterior distraction betweenvertebrae, the spacer 24 can be sized greater than the distance betweenopposing surfaces of the vertebral anchors 14, 16 upon which the spacer24 engages. This measurement may be made, for example and withoutlimitation, based on the distance outside the patient betweeninstruments engaging the anchors or through radiographic means.

After the spacer 24 has been advanced along the connecting element 22,the second portion 96 of the connecting element 22 may extend generallytoward the first incision 30 before being received in the receivingchannel 42 of the first vertebral anchor 14 or the elongated slot 58 ofthe first positioning tool 50. The second portion 96 of the connectingelement 22 may therefore be moved to a desired position relative to thefirst vertebral anchor 14 by manipulating the connecting element 22 byhand or by using one or more additional tools. For example, as shown inFIG. 3E, a tensioning tool 150 configured to cooperate with the firstpositioning tool 50 may be inserted through the first incision 30. Thetensioning tool 150 includes a stabilizing element 152 having a topportion 154 aligned generally above the second end 100 of the spacer 24.A bottom portion 156 of the tensioning tool 150 may be inserted throughthe elongated slot 58 to an opposite side of the first positioning tool50 to direct the second portion 96 of the connecting element 22 into thereceiving channel 42 (FIG. 2) of the first vertebral anchor 14. When thesecond portion 96 is received in the receiving channel 42, the spacer 24is properly positioned between the first and second vertebral anchors14, 16.

Additional length 104 of the connecting element 22 extending from thesecond portion 96 may curve upwardly and around the bottom portion 156of the stabilizing element 152 so as to extend into the elongated slot58 of the first positioning tool 50. Indeed, the additional length maycontinue to extend out of the elongated slot 58 and through the topportion 154 of the stabilizing element 152. While maintaining the bottomportion 156 of the stabilizing element 152 in position (so that thesecond portion 96 of the connecting element 22 is maintained in thereceiving channel 42), the additional length 104 may be pulled to placethe connecting element 22 in tension. The additional length 104 may bepulled manually by hand or by using a surgical tool. In one embodiment,the tensioning tool 150 further includes a gripping element 158 having afirst arm 160 configured to clamp or otherwise securely grip theconnecting element 22 after the additional length 104 extends throughthe stabilizing element 152. As shown in FIGS. 3E and 3F, a surgeon maypivot the first arm 160 relative to a second arm 162 of the grippingelement 158 to mechanically pull the connecting element 22 through thestabilizing element 152.

Once the connecting element 22 is placed under a desired degree oftension, the second portion 96 is secured to the first vertebral anchor14. The second portion 96 may be secured in a manner similar to thefirst portion 74. To this end, a fastener 106, such as a set screw, maybe inserted through the first incision 30 and percutaneously deliveredto the receiving channel 42 of the first vertebral anchor 14. Morespecifically, the fastener 106 may be delivered through the stabilizingelement 152 and first positioning tool 50 using a driving tool 170,which may be similar to the driving tool 94 (FIG. 3C). A handle 172 ofthe driving tool 170 is rotated to drive the fastener 106 intoengagement with the internal threads 92 (FIG. 2) provided in thereceiving channel 42. The threaded engagement secures the second portion96 of the connecting element 22 relative to the first vertebral anchor14. The connecting element 22 may then be cut proximate the firstvertebral anchor 14, and the first positioning tool 50 and thetensioning tool 150 may be removed from the patient's body 12 throughthe first incision 30. This results in the arrangement shown in FIG. 3G.

FIG. 5 shows a delivery device 200 according to an alternativeembodiment. The delivery device 200 includes a first sheath member 202coupled to a second sheath member 204 at an articulating joint 206. Inthe illustrative embodiment shown in FIG. 5, the first sheath member 202is hollow so that it may be positioned over the connecting element 22 inthe same manner as the delivery device 70 (FIG. 3). The second sheathmember 204 may also be hollow, and may further include a slot 208 foraccommodating the connecting element 22. Alternatively, the secondsheath member 204 may be solid so that the connecting element 22 mayonly extend through the first sheath member 202.

Because of the articulating joint 206, the first sheath member 202 maypivot relative to the second sheath member 204 to change the angledefined between the two components. In one embodiment, the articulatingjoint 206 may be configured to lock the first sheath member 202 atseveral different angles relative to the second sheath member 204. Anysuitable locking technique may be used. For example, in a manner notshown herein, the articulating joint 206 may include a ratchetingmechanism, locking pin, or other structure capable of locking the firstsheath member 202 at one or more angles relative to the second sheathmember 204. In addition to this ability to adjust angular orientation,the first sheath member 202 may be designed to have an adjustablelength. For example, the first sheath member 202 may include telescopingor extendable sections (not shown).

FIGS. 5A-5C illustrate the delivery device 200 being used to deliver theconnecting element 22 to within the patient's body 12, with likereference numbers being used to refer to like structure from FIGS.3A-3G. The delivery device 200 may be inserted through the firstincision 30 within or near the first positioning tool 50. Additionally,the first sheath member 202 and/or second sheath member 204 may be atleast partially received in the elongated slot 58 of the firstpositioning tool 50 to help guide the first sheath member 202 generallytoward the second vertebral anchor 16. Although FIGS. 5A-5C illustratethe first sheath member 202 and second sheath member 204 havingdiameters smaller than the width of the elongated slot 58, those skilledin the art will appreciate that the diameters may alternatively begreater than the width of the elongated slot 58. To this end, thedelivery device 200 may be used in a manner similar to the deliverydevice 70 (FIG. 3A) or the delivery device 70′ (FIG. 4) depending on thediameters of the first sheath member 202 and second sheath member 204.

Although the techniques discussed above for guiding the delivery devices70, 70′ may still apply (engagement features, using the firstpositioning tool 50 for leverage, etc.), the delivery device 200 ismanipulated differently when passed through the first incision 30. Thisdifference is due to the first sheath member 202 being positioned at anangle relative to the second sheath member 204 (by means of thearticulating joint 206). In some instances it may be easier to use thedelivery device 200 to delivery the first portion 74 of the connectingelement 22 to the second vertebral anchor 16, whereas in other instancesit may be easier to use the delivery device 70. Note that the angle ofthe first sheath member 202 relative to the second sheath member 204 maybe adjusted one or more times during the insertion of the deliverydevice 200. Alternatively, the angle may be adjusted prior to insertionand maintained throughout the procedure.

After using the delivery device 200 to deliver the first portion 74 ofthe connecting element 22 to the second vertebral anchor 16, the firstportion 74 may be secured to the second vertebral anchor 16 in the samemanner discussed above with reference to FIG. 3C. The delivery device200 may then be removed from the patient's body 12 by retracting it backthrough the first incision 30 and over the connecting element 22. Aswith the insertion procedure, the angle of the first sheath member 202relative to the second sheath member 204 may be adjusted before orduring this removal procedure. After the delivery device 200 is removed,the spacer 24 may be advanced over the connecting element 22 and thesecond portion 96 may be secured to the first vertebral anchor 14, asdiscussed above with reference to FIGS. 3D-3G.

The embodiments described above relate to using the stabilization system10 as part of a single-level treatment (i.e., between two adjacentvertebrae). However, it will be appreciated that the same techniques andtools may be used as part of a multi-level treatment as well. Forexample, FIGS. 6A-6C illustrate a third vertebra 300 positioned betweenthe first and second vertebrae 18, 20 and a method of installing astabilization system to effect treatment across the first, second, andthird vertebrae 18, 20, 300. Because the techniques and tools aresimilar to those discussed above with reference to FIGS. 3A-3G, likereference numbers are used to refer to like structure.

In this embodiment, a third vertebral anchor 302 may be inserted througha third incision 304 at a third location on the patient's skin 28 andultimately secured to the third vertebra 300 using conventionaltechniques. A third positioning tool 306 may then be inserted throughthe third incision 304 and generally toward the third vertebral anchor302. The third vertebral anchor 302 may be a pedicle screw havingsubstantially the same construction as the first and second vertebralanchors 14, 16, and the third positioning tool 306 may havesubstantially the same construction as the first and second positioningtools 50, 80. To this end, the third positioning tool 306 may include anelongated slot or cavity (not shown). Additionally, a third end 310 ofthe third positioning tool 306 may be coupled to the head 36 of thethird vertebral anchor 302 using the techniques discussed above withreference to the first and second positioning tools 50, 80.

After the first, second, and third positioning tools 50, 80, 306 arecoupled to the first, second, and third vertebral anchors 14, 16, 302,respectively, the delivery device 70 and connecting element 22 may beinserted through the first incision 30. The first positioning tool 50 isused to facilitate directing the delivery device 70 generally toward thethird vertebral anchor 302. Once the delivery device 70 contacts thehead 36 of the third vertebral anchor 302 or the third positioning tool306, the connecting element 22 may be pushed through the delivery device70 so that a third portion 312 (located between the first portion 74 andsecond portion 96) extends through the receiving channel 42 (FIG. 2) inthe third vertebral anchor 302 or through the elongated slot of thethird positioning tool 306. In some embodiments, the connecting element22 may have a preformed curvature so that it curves upwardly andgenerally toward the second incision 32 when further pushed through thedelivery device 70. The first portion 74 may be received in theelongated slot 86 and/or ultimately exit the patient's body 12 throughthe second incision 32. In other embodiments, the connecting element 22approaches the second vertebral anchor 16 when further pushed throughthe delivery device 70. The first portion 74 may then be received in theelongate slot 86 and pulled up through the second incision 32.

Once the connecting element 22 is pushed sufficiently through thedelivery device 70, the third portion 312 may be secured to the thirdvertebral anchor 302 using any suitable technique. For example, thethird portion 312 may be retained in the receiving channel 42 (FIG. 2)of the third vertebral anchor 302 by passing a fastener 314, such as aset screw, through the elongated slot or cavity of the third positioningtool 306 and securing the fastener 314 within the receiving channel 42over the third portion 312. The delivery device 70 may then be pulledback through the first incision 30 and removed from the connectingelement 22 so as to expose the second portion 96. At this point, thethird portion 312 is secured within the patient's body 12 whereas thefirst and second portions 74, 96 are positioned in or proximate theelongated slots 58, 86, respectively. Such an arrangement allowsspacers, like spacer 24, to be placed over the connecting element 22 andfor the first and second portions 74, 96 to be secured to the first andsecond vertebral anchors 14, 16 using the techniques described above.For example, the tensioning tool 150 (FIGS. 3E and 3F) and fastener 106may be used to secure the second portion 96 to the first vertebralanchor 14, and the tensioning tool 150 and fastener 84 may be used tosecure the first portion 74 to the second vertebral anchor 16. Anyadditional length of the connecting element 22 extending beyond thefirst and second portions 74, 96 may be cut proximate the first andsecond vertebral anchors 14, 16 to complete the installation procedure.

In one embodiment, the surgeon can be provided with several spacers eachhaving different elastic characteristics for the multi-level constructshown in FIGS. 6A-6C. The surgeon can choose the spacer, like spacer 24,based on the patient's condition and include spacers having differentelastic characteristics in a single patient, if desired. For example,the spacer between anchors 14 and 302 can be a more elastic material andthe spacer between anchors 302 and 16 can be a more rigid material.

In another embodiment, the surgeon can be provided a single connectingelement that has varying elastic characteristics over its length for themulti-level construct shown in FIGS. 6A-6C. The surgeon may then implantthe elastically varied connecting element in a desired location toprovide a desired result in the patient. For example, the elasticallyvaried connecting element can include radiographic markers that assistthe surgeon in identifying the differing areas of elasticity when theconnecting element is implanted in the patient to provide differingcharacteristics of the stabilization system 10 at adjacent levels.

FIGS. 7A-7C illustrate another method of installing the stabilizationsystem 10 for the purpose of multi-level treatment. Because the methoduses many of the same components as the method shown in FIGS. 6A-6C,like reference numbers are used to refer to like structure.Additionally, only the differences between the methods are describedbelow.

In this embodiment, a delivery device 400 is positioned over theconnecting element 22. The delivery device 400 comprises a first sheathmember 402 and a second sheath member 404, which may or may not havesubstantially the same shape and/or length. The delivery device 400 andconnecting element 22 are inserted through the first incision 30 andalong at least a portion of the first positioning tool 50 before thethird end 310 of the third positioning tool 306 is coupled to the head36 of the third vertebral anchor 302. Although FIG. 7A shows the firstsheath member 402 spaced apart from the second sheath member 404 suchthat the third portion 312 of the connecting element 22 is exposedwithin the patient's body 12, the second sheath member 404 mayalternatively be advanced over the third portion 312 during thisinsertion so as to abut the first sheath member 402.

Eventually the first sheath member 402 is directed past the thirdvertebral anchor 302 so that the third portion 312 of the connectingelement 22 is positioned proximate the head 36 of the third vertebralanchor 302. If the second sheath member 404 abuts the first sheathmember 402, the second sheath member 404 is retracted to expose thethird portion 312. The third positioning tool 306 may then be directeddownwardly to the third vertebral anchor 302 so that the third portion312 is received in the elongated slot or cavity of the third positioningtool 306. After coupling the third end 310 of the third positioning tool306 to the head 36 of the third vertebral anchor 302, the third portion312 may be secured to the third vertebral anchor 302 using the fastener314 or any other suitable technique.

Advantageously, the first sheath member 402 has a preformed curvature sothat it curves slightly upwardly toward the patient's skin 28 afterbeing advanced past the third vertebral anchor 302. The first sheathmember 402 may eventually contact the second positioning tool 80, whichmay be used to facilitate directing the first sheath member 402 to thesecond incision 32. For example, the first sheath member 402 may be atleast partially received in the elongated slot 86 and may slide alongthe elongated slot 86 when further advanced past the third vertebralanchor 302.

After the third portion 312 of the connecting element 22 is secured tothe third vertebral anchor 302, the first and second sheath members 402,404 may be removed from the patient's body 12 and connecting element 22.More specifically, the first sheath member 402 may be removed throughthe second incision 32 and from the connecting element 22 so as theleave the first portion 74 positioned in or proximate the elongated slot86. The second sheath member 404 may be removed back through the firstincision 30 and off the connecting element 22 so as to leave the secondportion 96 positioned in or proximate the elongated slot 58. At thispoint, the first portion 74 may be secured to the second vertebralanchor 16 and the second portion 96 may be secured to the firstvertebral anchor 14 using any of the techniques discussed above. It willbe appreciated that the third positioning tool 306 may be removedthrough the third incision 304 before or after removing the first andsecond sheath members 402, 404 and/or securing the first and secondportions 74, 96.

FIGS. 8A-8D illustrate yet another method of installing thestabilization system 10 for the purpose of multi-level treatment. Likereference numbers are once again used to refer to like structure fromthe other embodiments discussed above.

In this embodiment, the first, second, and third positioning tools50,80, 306 are inserted through the respective first, second, and thirdincisions 30, 32, 304 and coupled to the respective first, second, andthird vertebral anchors 14, 16, 302. The connecting element 22 isinserted through the elongated slot in the third positioning tool 306 sothat the first portion 74 extends generally toward the first positioningtool 50 and the second portion 96 extends generally toward the secondpositioning tool 80. A first delivery device 500 may then be positionedover the first portion 74 and a second delivery device 502 may bepositioned over the second portion 96. The first and second deliverydevices 500, 502 may be used to direct the first and second portions 74,96 through the patient's body 12.

For example, the first delivery device 500 and the first portion 74 ofthe connecting element 22 may be inserted through the third incision 304and along at least a portion of the third positioning tool 306. Thethird positioning tool 306 may be used for guidance and/or leverage tohelp direct the first delivery device 500 and first portion 74 along apath through the patient's body 12 and generally toward the firstvertebral anchor 14. To this end, the third positioning tool 306 and itselongated slot may be used in a way similar to which the firstpositioning tool 50 and elongated slot 58 are used in the otherembodiments discussed above. When the first delivery device 500 contactsthe first vertebral anchor 14 and/or first positioning tool 50, it maybe directed upwardly toward the first incision 30. For example, thefirst delivery device 500 may slide along the elongated slot 58 and exitthe patient's body 12 through the first incision 30 when sufficientlyadvanced through the third incision 304. The tissue 72 within thepatient's body 12 helps maintain the first delivery device 500 andconnecting element 22 within the patient's body 12 between the first andthird incisions 30, 304.

The second delivery device 502 and second portion 96 of the connectingelement 22 may be inserted into the patient's body 12 in a similarmanner. Specifically, the second delivery device 502 and second portion96 may be inserted through the third incision 304 and generally towardthe second vertebral anchor 16, using the third positioning tool 306 forguidance and/or leverage when needed. When the second delivery device502 contacts the second vertebral anchor 16 and/or second positioningtool 80, it may be directed upwardly toward the second incision 32. Forexample, the second delivery device 502 may slide along the elongatedslot 86 toward the second incision 32.

Next, the third portion 312 of the connecting element 22 may be pusheddownwardly through the third positioning tool 306 and into the receivingchannel 42 (FIG. 2) in the head 36 of the third vertebral anchor 302.Any suitable tool may be used to push the third portion 312, includingthe fastener 314 and driving tool 94 ultimately used to retain the thirdportion 312 within the receiving channel 42. As the third portion 312 ispushed downwardly, the first and second delivery devices 500, 502 arefurther advanced into the patient's body 12 as well. Thus, the firstdelivery device 500 eventually extends from the third vertebral anchor302 to the first incision 30 and the second delivery device 502eventually extends from the third vertebral anchor 302 to the secondincision 32. After securing the third portion 312 to the third vertebralanchor 302 using the fastener 314 or any other suitable technique, thefirst and second delivery devices 500, 502 may be removed from thepatient's body 12 through the respective first and second incisions 30,32. Removing the first and second delivery devices 500, 502 exposes thefirst and second portions 74, 96, which may be secured to the respectivefirst and second vertebral anchors 14, 16 using any of the techniquesdiscussed above.

While the invention has been illustrated by the description of one ormore embodiments thereof, and while the embodiments have been describedin considerable detail, they are not intended to restrict or in any waylimit the scope of the appended claims to such detail. Additionaladvantages and modifications will readily appear to those skilled in theart. For example, although the positioning tools are described above asbeing inserted through the same incisions used to inserted the vertebralanchors, the positioning tools may alternatively be inserted throughseparate incisions. Moreover, in an open surgical procedure there may beone or more large incisions through which two or more of the positioningtools are inserted. The invention in its broader aspects is thereforenot limited to the specific details, representative apparatus andmethods and illustrative examples shown and described. Accordingly,departures may be made from such details without departing from thescope or spirit of the inventor's general inventive concept.

What is claimed:
 1. A surgical method, comprising: implanting a firstbone anchor in a first vertebra; implanting a second bone anchor in asecond vertebra; routing a flexible connector into a second receivingchannel in a head of the second bone anchor; securing the flexibleconnector in the second receiving channel using a second fastener;inserting a tensioning tool through a first incision and engaging aportion of the flexible connector proximate a head of the first boneanchor with the tensioning tool; directing the flexible connector into afirst receiving channel in the head of the first anchor using a portionof the tensioning tool; tensioning the flexible connector between thefirst and second bone anchors using the tensioning tool; and securingthe flexible connector in the first receiving channel with the flexibleconnector in tension between the first and second bone anchors using afirst fastener.
 2. The surgical method of claim 1, further comprising:selecting the flexible connector from a plurality of flexibleconnectors, wherein each flexible connector of the plurality of flexibleconnectors includes a different elasticity.
 3. The surgical method ofclaim 2, wherein selecting the flexible connector includes evaluating acondition of at least a portion of a spine of a patient.
 4. The surgicalmethod of claim 1, further comprising implanting a third bone anchor ina third vertebra.
 5. The surgical method of claim 4, further comprisingrouting the flexible connector into a third receiving channel in a headof the third bone anchor using the portion of the tensioning tool. 6.The surgical method of claim 5, further comprising tensioning theflexible connector between the third bone anchor and at least one of thefirst bone anchor or the second bone anchor with the tensioning tool. 7.The surgical method of claim 6, further comprising securing the flexibleconnector in the third receiving channel with the flexible connector intension using a third fastener.
 8. The surgical method of claim 1,wherein routing the flexible connector into the second receiving channelincludes passing the flexible connector through a flexible deliverydevice.
 9. The surgical method of claim 8, wherein routing the flexibleconnector includes manipulating the flexible delivery device throughanatomy, the flexible delivery device including a rigidity greater thana rigidity of the flexible connector.
 10. The surgical method of claim1, wherein the first and second fasteners comprise set screws, and theflexible connector is fastened into the first and second receivingchannels by engaging the set screws with internal threads of the firstand second receiving channels and advancing the set screws into a lockedposition.
 11. The surgical method of claim 10, wherein the first andsecond fasteners are advanced in the first and second receiving channelsusing a driving tool.
 12. The surgical method of claim 1, whereintensioning the flexible connector includes manipulating a first arm anda second arm of the tensioning tool.
 13. The surgical method of claim12, wherein manipulating the first arm and the second arm includesadvancing the first arm towards the second arm to put tension on theflexible connector.
 14. A method for implanting a spinal stabilizationsystem, the method comprising: inserting a flexible cord into a firstreceiving channel in a head of a first bone anchor, the first boneanchor previously secured to a first vertebral body; securing theflexible cord in the first receiving channel using a first set screw;engaging a portion of the flexible cord with a portion of a tensioningtool; directing the flexible cord into a second receiving channel in ahead of a second anchor using the portion of the tensioning tool, thesecond bone anchor previously secured to a second vertebral body;tensioning the flexible cord between the first bone anchor and thesecond bone anchor using the tensioning tool; and securing the flexiblecord in the second receiving channel with the flexible cord in tensionbetween the first bone anchor and the second bone anchor using a secondset screw.
 15. The method of claim 14, further comprising selecting theflexible cord from a plurality of flexible cords, wherein each flexiblecord of the plurality of flexible cords includes a different elasticity.16. The method of claim 14, further comprising implanting a third boneanchor in a third vertebra.
 17. The method of claim 16, furthercomprising directing the flexible cord into a third receiving channel ina head of the third bone anchor using the portion of the tensioningtool.
 18. The method of claim 17, further comprising tensioning theflexible cord between the third bone anchor and at least one of thefirst bone anchor or the second bone anchor with the tensioning tool.19. The method of claim 18, further comprising securing the flexiblecord in the third receiving channel with the flexible cord in tensionusing a third set screw.
 20. The method of claim 14, wherein directingthe flexible cord into the first receiving channel includes passing theflexible connector through a flexible delivery device, and whereindirecting the flexible cord further includes manipulating the flexibledelivery device through anatomy, the flexible delivery device includinga rigidity greater than a rigidity of the flexible cord.